1. Field of Invention
The present invention relates generally to fluid level control, and more particularly to maintaining a desired water level in a swimming pool.
2. Background Art
Swimming pool owners know how important it is to maintain the correct level of water in a swimming pool, so that the skimmer has sufficient water flow to keep the circulation pump from running dry and resulting in pump and motor failure. It is possible to draw water from the bottom drain of the pool. However, to do so, the skimmer is bypassed, and floating trash blown into the pool will not be collected. If the floating trash is permitted to remain in the pool, much of it will eventually sink to the bottom and much of this trash will be sucked up from the bottom drain only to be deposited in the small collecting basket in the circulation pump. The basket in turn will eventually clog, and the result to the pump and pump motor will be the same as if the skimmer was without water flow. In addition, the pool clean-up job, if only the bottom drain is used, would become difficult.
There are several factors that cause the water level in the pool to drop below that necessary for the proper use of the skimmer and circulating pump. Water evaporates from sun and wind. Water is splashed out of the pool by active pool users. A slow leak occurs in the pool itself. It is therefore important to be able to maintain the water level within the pool, typically within plus or minus an inch, for proper functioning of the skimmer. Pool owners who are away from home for more than a few days at a time must depend on neighbors and friends to check on the water level of their pool. Each day, water must be added as necessary to keep the proper circulation through the skimmer and to avoid pump and motor breakdown. The peace of mind acquired by the use of a device to maintain a constant pool level is a well-known need in the industry. There are many devices available to the pool owner. Some are intended for industrial use and not specifically designed for swimming pool use, where wave action is often present. Of those intended for swimming pool use, most are expensive and are intended to be installed when the pool is being built.
U.S. Pat. No. 4,586,532 to Tsolkas discloses a liquid level actuator for sensing changes in liquid levels in a pool and adjusting the flow of the liquid into the pool to maintain the level at a selected height. The apparatus disclosed includes a base member, a liquid conduit mounted on the base member, an arm hingedly mounted on the base member proximate a delivery end of the conduit, a stopper fixed to the arm and arcuately moveable into and out of engagement with the conduit delivery end. A flotation body is fixed to a free end of the arm and adapted to be engaged by the liquid in the pool and buoyed at a level representative of pool level. Wave activity at the pool water surface causes the float to oscillate causing rapid fluctuations of water supplied to the pool. Such rapid fluctuations cause rapid on and off action to the water supply, which ultimately results in damaged supply conduit or source. U.S. Pat. No. 3,908,206 to Grewing discloses an automatic water level keeper for swimming pools that is located adjacent an upper rim of an above-ground swimming pool. The water levels in the pool and in a water tank of the device are equalized and a water supply line is connected to a float valve in the tank for providing make-up water for the swimming pool when the water level in the pool falls below a predetermined height of the water level in the tank. Such a structure is not easily adaptable for use in an in-ground pool and is typically installed as a permanent device. U.S. Pat. No. 4,574,405 to Tams discloses a water level control device adapted to be detachably mounted within a swimming pool at a desired water level. A float-controlled valve is mounted within a housing, wherein the float is responsive to changes in water level of the swimming pool. A water inlet and outlet are located outside of the housing, so as to prevent turbulence within the housing. U.S. Pat. No. 4,592,098 to Magnes for a liquid level control system includes a primary float valve, which allows liquid to flow into a pool reservoir when the level of the fluid in the reservoir is below a first predetermined level, and a secondary float valve associated with the primary flow valve, which shuts off the flow of fluid into the pool reservoir when the level of the liquid in the pool reservoir exceeds a second predetermined level which is higher in elevation than the first predetermined level. In operation, if the expected operation of the primary valve is prevented for any reason and the primary valve sticks or remains in an open condition allowing the liquid in the reservoir to reach a second predetermined level, the secondary valve terminates the flow of liquid from the source into the flow chamber.
The devices disclosed, and in many of the devices available, positive action to prevent siphoning from the pool into the water supply system is not taken. Further, many of the devices available lend themselves well to permanent installation of below-ground pools, but fall short of providing an easy and inexpensive portable system for use with such an in-ground pool.